Compositions for cosmetic use, more specifically for bath, and comprising compounds that are incompatible with each other that form layers when at rest imparting a different aspect to the cosmetic product are known from the prior art. Most of those known products contain at least one oily portion and an aqueous portion in addition to at least one surfactant compound.
Compositions consisting of two or more types of oil that are not compatible, or combinations of water/oil/alcohol, each component being incompatible with each other, or even emulsion-type compositions with one aqueous phase and one layer of alcohol are also known. Those compositions layers are mixed by a stirring step carried out by the end user at the moment of using the product.
Document EP0882442 (Shiseido) teaches a light-texture multi-layer composition that discloses the presence of a surfactant as an essential component which is the compound that supplies the main technical effect of the invention, that is to say, the effect of lightness of the product.
The so-called lightness of the product or a light-texture product related to cosmetic compositions, more specifically the compositions used during or after the bath, may be understood as being the ease of removing the product from the skin, as for instance, when the product is washed away by the water.
This characteristic is not always desired by the user since there are those who prefer products that leave behind on the skin a residual film that gives them a feeling of softness, hydration and brightness.
Document JP 4290810 teaches a composition having three layers: an oily layer, a surfactant layer comprising 1 or more types of surfactants, and an aqueous layer. That composition is described as having a transparent appearance and good emulsification when stirred. After remaining at rest for some time, separation of the phases occurs.
Since a considerable amount of surfactant is used, that product may cause problems on the skin. Moreover, when it is formulated as a product for bath, the conditions of mixture are not good, forming the so-called “oil droplets”, causing an unpleasant feeling.
Document JP 10 1040413 (Max Fuakutac KK) describes the obtention of a 2-phase composition having one or more surfactants, and documents JP 63165304, JP 63165305, JP 63083009, JP 63083010, JP 63083011, JP 63033316 and JP 63033317 (Kanebo), disclose multilayer compositions in which a high percentage of surfactants is used, based on the total weight of the composition.
The surfactants belong to a class of raw materials that are known as primary irritants. Moreover, they interfere with the layers separation time, rendering the formation of the layers slower.
Another effect provided by the surfactant when mixed to a cosmetic composition is that it promotes the emulsification of the product, imparting a milky aspect when it is used in bathtubs or when applied to the body, which may be an undesirable effect for the end user.
The use of a surfactant emollient compound provides the solubilization of essential oils and their migration to the intermediate phase, which may nullify the essence that must be in the oily phase. This type of compound is generally used in cosmetic compositions in which the expected effect is that of a composition with a light formulation.
Another type of cosmetic composition that, has two layers is the so-called biphasic composition, that is to say, with at least one lower phase and one upper phase which :are designed for removing make-up.
Another drawback which the inventor has noticed in the known multilayer cosmetic compositions is that the use of dyes in a surfactant system is difficult to stabilize. They precipitate and migrate to other layers of the composition.